Question

Read the following passage and answer the question that follows.

Attempting to understand science and scientific reasoning in terms of the subjective beliefs of scientists would seem to be a disappointing departure for those who seek an objective account of science. Howson and Urbach have an answer to that charge. They insist that the Bayesian theory constitutes an objective theory of scientific inference. That is, given a set of prior probabilities and some new evidence, Bayes' theorem dictates in an objective way what the new, posterior, probabilities must be in the light of that evidence. There is no difference in this respect between Bayesianism and deductive logic, because logic has nothing to say about the source of the propositions that constitute the premises of a deduction either. It simply dictates what follows from those propositions once they are given. The Bayesian defence can be taken a stage further. It can be argued that the beliefs of individual scientists, however much they might differ at the outset, can be made to converge given the appropriate input of evidence. It is easy to see in an informal way how this can come about. Suppose two scientists start out by disagreeing greatly about the probable truth of hypothesis h which predicts otherwise unexpected experimental outcome e. The one who attributes a high probability to h will regard e as less unlikely than the one who attributes a low probability to h. So P(e) will be high for the former and low for the latter. Suppose now that e is experimentally confirmed. Each scientist will have to adjust the probabilities for h by the factor P(e/h)/P(e). However, since we are assuming that e follows from h, P(e/h) is 1 and the scaling factor is 1/P(e). Consequently, the scientist who started with a low probability for h will scale up that probability by a larger factor than the scientist who started with a higher probability for h. As more positive evidence comes in, the original doubter is forced to scale up the probability in such a way that it eventually approaches that of the already convinced scientist. In this way, argue the Bayesians, widely differing subjective opinions can be brought into conformity in response to evidence in an objective way.



Using the idea explicated in the passage above, the only scientific way to deny the validity of a counter-hypothesis put forward to explain a natural phenomenon would be to:

• A. Take the counter-hypothesis and try to find flaws in its components.
• B. Question the source of alternative hypothesis.
• C. Question the authority of the scientist stating the alternative hypothesis.
• D. Take the alternative explanation and ask for its fullest development in terms of possible ramifications other than the already existent outcome (e).

Hint:

Recall that the passage says logic has nothing to say about where a hypothesis comes from; a hypothesis is judged by its predictions, not its source.

Answer 1

The Correct Option is D

The passage sets up a simple structure: a hypothesis h predicts an outcome e, and when e is observed, belief in h goes up. The question asks what the passage's logic says is the only scientific way to reject a rival, counter-hypothesis that also tries to explain the same natural event.

1. Take the counter-hypothesis and try to find flaws in its components: This sounds reasonable in general, but it is not the method the passage actually describes. The passage's method works through predictions and evidence, not through picking apart the internal structure of a hypothesis.
2. Question the source of alternative hypothesis: The passage explicitly says logic, and by extension the Bayesian method it defends, has nothing to say about the source of the propositions. Where a hypothesis comes from is irrelevant to this framework, so this cannot be the scientific way to deny it.
3. Question the authority of the scientist stating the alternative hypothesis: This attacks the person, not the hypothesis, and has no place in the objective, evidence based method the passage describes.
4. Take the alternative explanation and ask for its fullest development in terms of possible ramifications other than the already existent outcome (e): This matches the passage's logic. A hypothesis only becomes testable, in the Bayesian sense described, when it makes a prediction that can be checked against evidence. If the counter-hypothesis explains only the outcome e that has already happened, it is doing no real work, since any hypothesis can be shaped after the fact to fit known evidence. The scientific move is to push the counter-hypothesis further, asking what else it predicts beyond e, and then test those further predictions. Only then can it be judged, and possibly denied, in the same objective way the passage describes for h.

The passage's whole argument rests on hypotheses being judged through their predictions against evidence, so a counter-hypothesis can only be scientifically denied by pushing it to make new predictions and checking those, not by attacking its source or its proponent.

Let's summarize:

• The passage's method judges hypotheses only through evidence and prediction, never through their origin or the credibility of the person proposing them.
• A hypothesis that merely fits an existing outcome after the fact has not been tested; asking for its further predictions is what makes a scientific verdict possible.

The correct answer is option 4.